On an island in the Adriatic Sea, an enemy missile base tests their impenetrable mine field and then prepares for launch. General Marin and Captain Strom watches as the satellite missile, equipped with nuclear missiles, successfully launches. Storm receives a call confirming that all control of the satellite has been transferred to them.
Jim picks up his tape briefing from a file cabinet in the back room of an art gallery. He’s informed that a hostile power launched the satellite and contains several thermonuclear bombs. The installation where the satellite is controlled from is protected by a minefield designed by an American defector, Arthur Norris. The IMF must destroy the satellite.
At the team briefing, Barney shows the team a mockup of one of the mines, and warns that the only way to disarm them is from a control panel within the installation. Paris informs them that Norris defected because he got in trouble with women and gambling. The enemies paid off his debts in return for his defection. Jim goes over the installation plans and explains that Barney will destroy the satellite by replacing a key unit with one of theirs. They have to substitute Paris for Norris in his apartment at the capital. Barney will land on the island by submarine while Jim gets the minefield plans from Norris’ office at headquarters. Paris won’t need a mask since Norris’ body type is too different. None of the operational personnel met Norris when he was working on the island, so Paris doesn’t think there’ll be any trouble.
Dana poses as a soldier and drives a truck to headquarters, and Jim leaves the back through a roof hatch and enters a second-story window after disabling the alarm.
Barney swims onto the island from the submarine.
Jim enters the security office and uses an x-ray device to get the safe open. He places a frame on front of the safe and then goes to the wall behind it and fires a burst of x-rays through the safe to get an impression of the lock.
Paris and Doug go to Norris’ apartment but get no answer when they ring the doorbell. They pick the lock and go inside. There’s no sign of Norris but they find a photo of a woman. Paris recognizes her as Kathrine Berat, an entertainer who has been involved with Norris for the last three months.
At Kathrine’s apartment, Norris and Kathrine share a drink. He admits that he’s worried that he’s told her too much about his work for the government, but Kathrine assures him that she would never do anything to hurt him.
Once he has the plans, Jim crawls out the window and reenters the truck.
Kathrine asks Norris to trust her and he kisses her and leaves. As soon as he’s gone, Kathrine calls someone on the phone. She’s unaware that Norris has come back in. He shoots her and then puts her coat on her.
Once Jim signals that he’s in the back, Dana drives the truck away.
Norris drives Kathrine’s body to an alleyway and carries it away, leaving her purse in the car. After making a detour to dispose of the purse and the gun, Norris then goes to his apartment and the team is waiting for him. They dart him unconscious and Jim gives Paris the fake substitute IDs, signed by Norris' commanding officer, General Conrad Bloch.
Barney uses a mortar to set off the mines. Strom calls the bunker and they send up a flare. There’s no sign of anyone since Barney is outside the field, so they assume it’s a malfunction. Strom suggests to Marin they shut down the field until they can call Norris in. The general finally agrees and has Strom put in a call to have Norris sent to the island. Paris receives the notification and leaves for the helipad with the stolen plans. Doug assures Jim and Dana that Norris is still unconscious.
A cook finds Kathrine’s body dumped in the alleyway behind his restaurant.
Paris arrives on the island and is given an ID badge and escorted to the control center.
Inspector Koder of the secret police is called in by Detective Lieutenant Rab when Kathrine’s corpse is reported. Koder explains that Kathrine was one of his double agents and was supposed to report to him after she met with Norris, and they agree to have Norris brought in.
Paris tells Marin that the minefield requires maintenance and Strom takes offense, saying that he’s made sure that it was taken care of. However, Paris says that he’ll have to shut down the minefield. Marin refuses but Strom convinces him to shut down the sector that malfunctioned. Once Marin leaves, Strom apologizes, saying the general resents having to rely on an American for help.
Once the field is shut down, Barney cuts through the fence and makes his way across the field and past the guards into the computer center.
Jim and Dana have tea and wait in Norris’ apartment, and he assures her that the satellite will land nearby but there won’t be any explosion. They’re surprised when the doorbell rings. Koder and Rab are there, and pick the lock when they get no answer. By the time they get in, Jim has hid in the closet while Dana and Doug hide in the bedroom behind the door. Rab comes but sees nothing in the room and steps back out. Koder calls Bloch to find out about Norris. Bloch notes that Koder was the one who met with and cleared Norris, and Koder informs him that Kathrine has been shot dead. Meanwhile, the IMF team listen in on the conversation.
Barney finishes replacing the computer circuit with the IMF part and then leaves the computer center.
Bloch calls Marin and tells him that they believe that Paris has killed Kathrine and may be committing further sabotage. Marin has Strom place Paris under arrest and then reactivate the minefield. As Barney heads out, his mine detector goes off and he realizes that the field is live... and he’s trapped. Paris protests but Marin orders the guards to take him back to the mainland for interrogation.
Rab and Koder search the apartment and find no sign that Kathrine was there. Koder believes, accurately, that Norris shot Kathrine at her apartment and disposed of her body. Rab admits that he’s never met Norris and Koder says that he has and found him weak. The two men then leave the apartment to interrogate Paris. Once they’re gone, Jim, Doug, and Dana emerge from hiding. They realize they have to clear Paris so he can go back and shut down the minefield, keep Koder from seeing Paris since he met him before, and find out from Norris what he did with the body. And all before the satellite comes down and they have to make their escape. Jim and Doug remove Norris from the bedroom closet where they hid him, and Jim tells Doug to make Norris believe that he had a heart attack.
Barney watches as a handcuffed Paris is escorted to the helicopter and taken off the island.
When Norris wakes up in pain, Jim claims that he’s an interrogator and demands that that he confess to Kathrine’s murder. Doug comes in but Jim refuses to let him treat Norris until the defector confesses. Norris quickly breaks and explains that he told her that he was going to defect again to Asia. But he realizes she was a double-agent and shot her, and Jim demands to know what he did with the gun. Once they have the information, Doug goes to the basement where Norris had it and finds the murder weapon and the purse.
Paris is brought into Rab’s office and the detective tells him that he shot Kathrine. He then calls Koder and tells him that Paris is there, and Koder leaves his office. Jim, posing as a police officer, trips him and knocks him down the stairs, and Doug then needles him unconscious. Rab runs up and Doug tells him to get an ambulance.
With thirty-five minutes until the satellite comes down, Barney waits on the edge of the minefield. Inside, Marin tells Strom to have his men check the perimeter.
Rab tries to get Paris to confess and the IMF agent continues to profess his innocence. He admits that he had a drink with Kathrine at her apartment and Rab suggests that she made a slip and Paris shot her. Paris can’t account for his whereabouts since he doesn’t know where Norris was, and asks what proof Rab has. Smiling, Rab informs Paris that they have a witness and has Dana brought in. Initially she claims she saw Paris carry Kathrine’s body out of her apartment and dumped it in an alleyway. However, Paris realizes what she’s up to and asks why she was there. Dana says that she followed him to Kathrine’s apartment to say they were breaking up. He then says that she made a threat on the phone to kill Kathrine and accuses her of killing Kathrine. Dana finally breaks down and admits that she killed Kathrine in a jealous rage. She tells Rab where they can find the gun and the purse.
Rab calls in Doug, who is waiting outside still posing as an officer. He takes Dana away and Paris tells Rab that he needs to call the installation and have them shut down the minefield before it blows up. Marin has Strom shut it down and Barney makes his escape. Paris then leaves police headquarters and escapes with Jim, Doug, and Dana. On the beach, Barney watches as the satellite plummets out of the sky.